The invention relates to an improved writing instrument of ball and lead points of turn and push style.
The known writing instrument of U.S. Pat. No. 3,266,465 can be used only for the ball point but cannot be used for the lead point of a mechanical pencil because it does not have any mechanism whereby the lead point can be pushed out of the writing instrument.
The invention has improved the said instrument possibly for use with the lead point also without any separate knob to push down, by means of an axially movable and rotatable sleeve-type cam which has a transformed end cam edge, the contour of which preferably comprises two sloped ellipses which vertically reciprocate two followers for the ball and lead points respectively, said cam edge contour having a vertical upper linear portion which allows the lead point to be pushed out of the said instrument by sliding said follower for ball point will slide along said linear portion, said sleeve cam being fixed to an actuater cap which can rotate and move up-and-down also.